Prime Minister Arseniy Yatsenyuk has called for an emergency meeting of the UN Security Council after at least nine members of Ukraine's security forces were killed in clashes with pro-Russian separatists in eastern Ukraine.

Yatsenyuk told journalists on May 22 that Kyiv wanted to present evidence that Russia is attempting to escalate the conflict and disrupt the May 25 presidential election.

Ministry spokesman Bohdan Senk said eight troops died and 17 were injured overnight when separatists attacked a Ukrainian checkpoint about 20 kilometers south of separatist-controlled Donetsk, in the Volnovakha area.

However, AP reported that 11 Ukrainian troops were killed and 30 injured in the attack on the checkpoint in the village of Blahodatne, near Volnovakha.

AP journalists say three charred Ukrainian armored infantry vehicles, their turrets blown away, and several burned trucks stood at the site of the attack.

Senk said one Ukrainian soldier also died during clashes with separatists in the neighboring Luhansk region.

WATCH: A cafe owner in the eastern Ukrainian town of Slovyansk surveys the damage to her business she says was shelled overnight by government forces. (Reuters)

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The Russian Defense Ministry, meanwhile, said on May 22 that several trains carrying weapons and planeloads of troops have left the Belgorod, Bryansk, and Rostov regions along the border with Ukraine as part of a massive military pullout.

NATO chief Anders Fogh Rasmussen, speaking in Montenegro on May 22, said that limited Russian troop movements near the border with Ukraine "may suggest" preparations for a withdrawal.

Rasmussen said, "I hope this is the start of a full and genuine withdrawal."

He added, "If we see any meaningful, comprehensive and verifiable withdrawal, I would be the first to welcome it."

It was the first time since the start of the Ukrainian crisis that NATO has given any credence to Moscow's statements that it is withdrawing troops from near the Ukraine border.

The alliance says Russia had massed a force of around 40,000 soldiers in the area.

British Journalist Freed

Meanwhile, a Russian television channel says a British national working as a freelancer for the station has been released without charge after being detained by Ukrainian authorities.

The Kremlin-funded RT channel, formerly known as Russia Today, said on its website that Graham Phillips "was released after almost 36 hours of detention by various Kyiv security forces."

Phillips wrote on Twitter that he did not face any charges or deportation.

He said he was detained by Ukrainian soldiers after taking photographs and asking questions at a checkpoint on May 20 in the southeastern Ukrainian city of Mariupol.

Separately, two reporters from the Russian website LifeNews were arrested by Ukrainian troops near the city of Kramatorsk. Moscow has demanded their immediate release.

The United States said on May 20 that Ukrainian security services claimed the journalists were carrying antiaircraft missiles and fake credentials.